Bumping gaia.json for 2 gaia-central revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/d3b212e17cda
Author: Eric Chou <echou@mozilla.com>
Desc: Merge pull request #13733 from eric30/Bug-938472

Bug 938472 - Modify usage of Pair / Unpair because of interface change

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https://hg.mozilla.org/integration/gaia-central/rev/3a849fc281eb
Author: Eric Chou <echou@mozilla.com>
Desc: Bug 938472 - Modify usage of Pair / Unpair because of interface change